三层平板介质光波导计算，该平板波导主要由3层均匀介质构成，中间的芯层折射率为n1，厚度为d，芯区生长在折射率为n2的衬底上，芯区上面的覆盖层折射率为n3。这里考虑的是n1大于n2大于n3。-Three-layer flat-plate dielectric waveguide, the flat waveguide is composed of three uniform media, the refractive index of the middle layer is n1, the thickness is d, the core area is grown on the substrate with refractive index n2, The refractive index of the layer is n3. It is considered here that n1 is greater than n2 and greater than n3.